Save a sparse matrix to disk in numpy’s .npz format.
Note: This is not binary compatible with scipy’s save_npz().
Will save a file that can only be opend with this package’s load_npz().

Parameters:

filename (string or file) – Either the file name (string) or an open file (file-like object)
where the data will be saved. If file is a string or a Path, the
.npz extension will be appended to the file name if it is not
already there